Dog age calculator
Enter the age of a dog to see the human age that a 2020 study of Labrador retrievers gives for it, beside the age that the old rule of seven years to a dog year would give.
This answer is for the example values in the boxes above. A dog of 5 years. Change the boxes to see your own answer.
The formula is 16 times the natural logarithm of the dog's age in years, plus 31. It was fitted to Labrador retrievers from birth to 16 years old, and it is not veterinary advice.
How it works
The calculator takes the age in years and months, changes it to years, and applies the formula of Wang and others (Cell Systems, 2020): human age equals 16 times the natural logarithm of the dog’s age in years, plus 31. The study compared the DNA methylation of 104 Labrador retrievers, from birth to 16 years old, with that of 320 humans, and found a nonlinear relationship between the two.
The second row gives the human age by the old rule that a dog year is seven human years.
A worked example
For a dog of 5 years, 16 times the natural logarithm of 5 is 25.75, and adding 31 gives 56.75, which the calculator shows as 57 human years. The rule of seven gives 35.
At 1 year the formula gives 31 and the rule 7, at 2 years 42 and 14, at 10 years 68 and 70, and at 12 years 71 and 84. The formula gives a higher human age than the rule for a young dog and a lower one for an old dog.
What it leaves out
The study measured Labrador retrievers, so other breeds are not covered. The oldest dog of the study was 16 years old, and the calculator says so when you go past it. It is not veterinary advice, and it says nothing about a dog’s health or how long it will live.
Sources
Questions
How old is a dog in human years?
By the formula of a 2020 study a dog of 1 year is 31, 2 years is 42, 5 years is 57, 10 years is 68 and 12 years is 71 in human years.
Is one dog year seven human years?
The rule of seven is an old adage, and the 2020 study asks in its introduction whether it holds. It found a nonlinear relationship: a dog of 1 year is 31 human years and a dog of 12 is 71, where the rule gives 7 and 84.
What is the formula for dog years?
Human age equals 16 times the natural logarithm of the dog’s age in years, plus 31. The study fitted it to the DNA methylation of 104 Labrador retrievers, from birth to 16 years old, and of 320 humans.
Does the formula work for every breed?
The study measured Labrador retrievers only, so other breeds are not covered. The calculator gives the same answer for every breed.
Why does the calculator start at 8 weeks?
The formula gives a human age below 0 for a dog under 0.144 year, which is about 7.5 weeks. The calculator starts at 0.15 year, 8 weeks, the youngest age that the paper itself translates.
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